Method for operating a brushless and sensorless multiphase electric motor

Abstract

The invention relates to a method for operating a multiphase electric motor (4) which is brushless and sensorless, wherein at least two phase voltages (UU, UV, Uw) and at least two phase currents (IU, IV, IW) of the electric motor (4) are determined, wherein voltage vectors (Uab, Udq) are ascertained from the phase voltages (UU, UV, Uw) and / or current vectors (Iab, Idq) are ascertained from the phase currents (IU, IV, IW), wherein a position replacement signal (PES) is determined as a measure for the rotor position (θ) from the angle (α) of the current vectors (Iab, Idq) and / or of the voltage vectors (Uab, Udq), wherein a rotational variable (θ, ω) is calculated from the position replacement signal (PES), and wherein the electric motor (4) is controlled and / or regulated in accordance with the rotational variable (θ, ω).

Description

Technical Field

[0001] This invention relates to a method for operating a brushless and sensorless multiphase electric motor. The invention also relates to electric drives, particularly electric drives for regulating elements (regulating systems) of motor vehicles, having an electric motor operating according to the method. Background Technology

[0002] Electric motor-driven or operated regulating systems, such as window regulators, seat adjusters, door and sliding roof actuators, radiator fan actuators, pumps, and interior space blowers, typically have electric drives with controlled electric motors. For such electric drives, so-called brushless electric motors (brushless DC motors, BLDC motors) are increasingly used, in which the fragile brush elements of a rigid (mechanical) commutator are replaced by electronic commutation of the motor current.

[0003] Electric drives in motor vehicles are typically powered by a (high-voltage) battery, which serves as an internal energy storage unit. This battery supplies direct current (DC) energy to the electric motor. To convert the DC current into motor current, a current converter (inverter, commutator) is appropriately connected between the energy storage unit and the electric motor. The current converter has a bridge circuit, which receives DC current or DC voltage from the energy storage unit via an intermediate electrical loop. By pulse-width modulation (PWM) controlling or regulating the semiconductor switches in the bridge circuit, the motor current is generated as a multi-phase output current. The PWM signal pulses cause the semiconductor switches to switch between on and off states in a rhythmic manner.

[0004] During operation, the bridge circuit feeds the motor current (three-phase current) into the stator coils of the electric motor, which in turn generates a rotating magnetic field that rotates relative to the stator. The rotor of the electric motor here appropriately has a certain number of permanent magnets, in which the interaction between the permanent magnets and the rotating field generates the torque that causes the rotor to rotate.

[0005] The phases of the three-phase current generated by a bridge circuit and the corresponding rotating field are called (motor) phases. In a figurative sense, this is also understood as the stator coils (phase windings) and their corresponding connecting lines (phase ends) that are respectively assigned to such phases. These phases are connected, for example, at the star point of a star circuit.

[0006] For effective operation, it is necessary to supply current to the phases at the correct time. Therefore, accurately determining the relative positioning of the rotor and stator is essential for motor control / regulation.

[0007] Here, for example, one could conceive of observer-based control and / or regulation of an electric motor. In such an observer method, the so-called observer operates based on the system equations of the electric motor or drive. By comparing the expected motor state from the observer with the measured values, the actual state can be determined, and thus the rotational parameters, i.e., rotor positioning and / or speed, can be obtained.

[0008] Rotor positioning for positioning determination is obtained, for example, by means of an additional rotation sensor, such as a Hall sensor. However, such rotation sensors or encoders are very expensive, so positioning determination should preferably be performed without sensors.

[0009] Sensorless positioning determination, for example, relies on detecting the current and / or voltage signals induced by back electromotive force (EMF). This back EMF is induced by a rotating permanent magnet in the phase winding. The induced back EMF signal is proportional to the rotor speed, which disadvantageously provides little or no information for positioning determination to the motor control unit at low speeds or when the motor is stationary. The signal-to-noise ratio decreases, especially at low speeds. This limitation also exists for sensorless measurement methods based on magnetic flux. Consequently, positioning determination or identification is typically impossible below a threshold speed, making it difficult to ensure safe and reliable operation of the motor, particularly during start-up from a standstill or at low speeds.

[0010] To reach and / or exceed threshold speeds, it may be possible, for example, to orient the drive or rotor without knowing the exact rotor position, and then accelerate it using an acceleration ramp during step operation. For orientation, a voltage vector is typically used, which rotates the rotor to a predetermined position (start-up positioning). For this purpose, for example, one phase is connected to a reference potential, such as ground, while pulse-width modulated control signals are supplied to the remaining phases. The resulting magnetic field then orients the rotor, thereby transferring it to the defined start-up position.

[0011] Disadvantages include the need for relatively high motor or phase currents. Furthermore, the electric motor or rotor accelerates relatively slowly, requiring long start-up or startup times. Additionally, there is a risk of oscillation and synchronization field loss. The acoustic performance of this driver is also adversely affected by oscillation and high motor current.

[0012] Another possibility for positioning identification is to evaluate the anisotropic characteristics of the drive, such as the inductance of the phase windings related to rotor positioning. Advantageously, this method for positioning identification works even at low speeds and when the rotor is stationary. However, it is disadvantageous that this method can only be used with drives having characteristics, such as inductance, that are sufficiently dependent on rotor positioning. Furthermore, a relatively powerful measurement detection unit is required. Additionally, the acoustic characteristics of the electric motor are negatively affected during operation, resulting in a greater noise load. Summary of the Invention

[0013] The object of this invention is to describe a particularly suitable method for operating a brushless and sensorless multiphase electric motor. In particular, this method should enable the electric motor to operate efficiently and reliably, even at low speeds or when emerging from a standstill. A further object of this invention is to describe an electric drive having an electric motor operating in this manner.

[0014] According to the invention, this task is solved in terms of method using the features of claim 1, and in terms of actuator using the features of claim 10. Advantageous designs and improvements are the subject of the dependent claims. The advantages and designs of the enumerated methods can also be transferred to the actuator, and vice versa.

[0015] The method according to the invention is applicable to and configured for operating brushless and sensorless multiphase, especially three-phase, electric motors. The electric motors herein are particularly synchronized, preferably brushless DC motors for motor vehicles, such as regulating motors.

[0016] According to this method, at least two phase voltages and at least two phase currents of an electric motor are determined.

[0017] The phase voltage vector is obtained from the phase voltage and / or the phase current vector is determined from the phase current. The conjunction "and / or" should be understood here and in the following text as meaning that the features associated by this conjunction can be formed together or as alternatives to each other.

[0018] Here, voltage vector or current vector should be understood as their respective spatial vectors, that is, the representation of the physical parameters of a three-phase or multi-phase system, especially a three-phase electric motor, i.e., a (spatial) vector or vector in a coordinate system of the complex plane. Here, the complex plane is essentially arranged in the cross-sectional plane of the electric motor.

[0019] Then, a positioning substitution signal is determined as a metric for rotor positioning based on the (phase) angle of the current vector and / or the (phase) angle of the voltage vector. Rotational parameters of the electric motor, such as (filtered) rotor positioning and / or rotational speed or velocity, are calculated based on the positioning substitution signal. The electric motor is then controlled and / or adjusted based on the calculated rotational parameters. This achieves a particularly suitable method.

[0020] Therefore, adjustment and / or control rely on positioning substitution signals or angles. In other words, positioning substitution signals or angles are essentially for the effective error (error signal) or effective regulation difference in the operation of the electric motor.

[0021] The required rotational parameters for controlling and / or regulating the electric motor are calculated based on angular parameters derived from voltage and / or current vectors or from positioning substitution signals. Compared to existing technologies, the rotational parameters of the electric motor are therefore not determined based on induced current and / or voltage signals or back electromotive force (EMF). Thus, this method is applicable even at low motor speeds or when starting from a standstill. This reduces the required speed at which the regulation method can be applied to operate the electric motor. In particular, regulation and / or control can therefore be achieved in a simple manner and method even at low speeds, without the electric motor needing to possess special motor characteristics, such as a sufficiently high correlation between inductance and rotor positioning.

[0022] According to this method, the exact or precise positioning of the electric motor is therefore unknown. A positioning substitution signal is used to replace the conventional positioning signal from the encoder or positioning sensor for control and / or regulation. This signal is processed, for example, by an observer (monitor), such as filtering, and rotational parameters are calculated or estimated. In other words, the positioning substitution signal is used as input to an observer, which filters the positioning substitution signal and determines the rotor positioning and / or rotational speed or velocity.

[0023] This method is particularly applicable when the motor speed is low, i.e., at a speed where there is insufficient back electromotive force available. The method terminates, for example, when a predetermined duration has elapsed or when a stored threshold speed is exceeded. The threshold speed is selected, for example, such that a sufficient back electromotive force signal is generated for conventional sensorless control and / or regulation methods when the motor speed exceeds the threshold speed.

[0024] Compared to the "fuzzy" rotational field prediction, the method according to the invention achieves a higher starting torque for the electric motor, and thus shortens the start-up time. Furthermore, it improves the efficiency and acoustic performance of the electric motor. This significantly improves the robustness of the electric motor at lower speeds.

[0025] Compared to classical or traditional sensorless positioning and identification, the method according to the invention does not require additional test pulses, thus avoiding acoustic damage and ensuring particularly simple integration. Compared to classical sensorless methods, the method according to the invention is particularly robust to measurement noise and tolerances. Furthermore, the method according to the invention is particularly easy to implement and parameterize, thereby ensuring exceptionally low computational load.

[0026] The method according to the invention is particularly suitable for applications where inductance is independent of positioning. This means that, for example, in a d / q coordinate system with the rotor relatively fixed, the inductances are equal (Ld = Lq), in which case there is no magnetic asymmetry as in electric motors or synchronous motors, and no reluctance contribution to torque is generated. This means that conventional methods, such as the INFORM method (indirect flux determination via online reactance measurement), are not applicable. In contrast, the method according to the invention can be used not only for positioning-dependent inductances (Ld ≠ Lq) but also for positioning-independent inductances (Ld = Lq).

[0027] The method according to the invention does not require initial positioning identification. Preferably, the control and / or regulation of the electric motor are automatically synchronized.

[0028] Without targeted initialization, the positioning substitution signal and the rotor are positioned relative to each other in a substantially random manner. However, this may cause the rotor to briefly accelerate in the opposite direction during startup or start-up. This is not serious and is permissible for many applications. However, to avoid this reverse startup and generally improve startup behavior, the method according to the invention can also be combined with an initial positioning method or a positioning identification method. This means that the method according to the invention is initialized together with the detected rotor positioning.

[0029] In the initial process starting from a stationary state, the initial unknown (initial) starting value can be determined at least approximately by means of positioning and identification measures (such as the INFORM method).

[0030] The underlying idea of ​​this invention is to completely avoid or at least reduce the influence of current noise during location identification. In the case of classic EMK identification, the inductance is set to zero, so that the current vector and voltage vector overlap in the static state. Furthermore, this allows for a simple and appropriate transition to classic location identification. In other words, for example, it is possible to specifically consider the error of the inductance (L=0) in order to reduce or completely avoid errors caused by measurement errors or inaccuracies.

[0031] In a favorable improvement, the angle used to determine the positioning substitution signal is determined based on the difference between the angles of the current vector and the voltage vector. In other words, the positioning substitution signal is determined based on the relative phase of the current vector and the voltage vector. This achieves a particularly suitable positioning substitution signal.

[0032] If the phase voltage vector leads the current vector, the angle or positioning substitution signal will have a low value, for example. During control and / or regulation, the electric motor is subsequently accelerated, in particular. Conversely, when the current vector leads the voltage vector, a relatively large difference in angle or positioning substitution signal is generated, resulting in a high value for the electric motor, for example, causing it to decelerate.

[0033] In a conceivable design, the additional phase angle is considered when determining the angle. This simplifies the implementation of the method and / or reduces systematic errors.

[0034] This is advantageous, for example, when adjusting the current along the q-direction of the positioning estimate, because the positioning direction and the current vector therefore have a 90° offset. The determination of the angle or positioning substitute signal can thus be simplified by using the difference between the sum and offset of the (phase) angles of the voltage vector. Therefore, it is unnecessary to additionally determine the angle of the current vector.

[0035] In another design approach, the positioning direction and phase voltage vector will have a 90° deviation in the electric motor's calibration state, thus allowing the deviation to be taken into account accordingly.

[0036] In a preferred configuration, the electric motor is controlled and / or regulated such that the angle is minimized. Specifically, the relative phase between the current vector and the phase vector is minimized. Here, for example, the voltage drop across the inductor and / or resistor is fully or partially accounted for. Preferably, this angle, or relative phase angle, is adjusted to zero. In other words, the electric motor is controlled and / or regulated such that the phase current and phase voltage have as much phase as possible. This reduces the impact of measurement errors and tolerances, thereby ensuring particularly reliable and safe operation of the electric motor.

[0037] In one conceivable implementation, the phase voltage, in particular, is controlled and / or regulated based on rotational parameters for controlling and / or regulating the electric motor. In other words, operation of the electric motor with regulated / controlled phase voltage is achieved. This enables more suitable and less energy-intensive operation of the electric motor.

[0038] In one possible improvement, the rotational parameters are calculated and limited based on the saved minimum speed (minimum speed). The minimum speed is understood here as the minimum rotational speed or minimum degree of rotation of the rotor, such as 10 revolutions per minute (RPM).

[0039] This additional functionality is integrated into the observer, for example. This essentially means that the rotational speed of the observer used to calculate the rotational parameters is limited to a minimum. Therefore, even when the values ​​at the observer's input remain constant, the calculated rotational parameters increase with a minimal gradient. In other words, the rotational parameters increase even when the positioning substitution signal is constant.

[0040] Minimum speed is specifically understood as a certain speed range or rotational speed range of the rotor. The upper limit of the minimum speed is chosen here to drive a stationary rotor, i.e., to prevent rotor slippage. The lower limit of the minimum speed is the speed at which sufficient EMK effect is caused. If the rotor speed is below the lower limit, the minimum speed will subsequently cause the electric motor or rotor to accelerate in order to increase the back EMF when calculating rotational parameters. Furthermore, this ensures that the electric motor does not start or start in the wrong direction (opposite direction).

[0041] By appropriately selecting the starting speed and minimum rotational speed, the method ensures self-synchronization, thus virtually eliminating the need for initial positioning identification. This enables reliable and safe starting of the electric motor.

[0042] Preferably, the minimum speed is adjusted or changed depending on the operating point or operating conditions of the electric motor. In a suitable design, the value of the minimum speed is adjusted in particular with respect to temperature. In other words, the value of the minimum speed preferably varies depending on the operating temperature. This achieves a particularly flexible method that matches the individual operating conditions or operating temperature of the electric motor.

[0043] Additionally or alternatively, it is conceivable that the minimum speed changes or varies over a period of time, such as during the start-up process. Therefore, it is advantageous to select a minimum speed that is low or equal to zero in order to better capture the rotor with the resulting rotational field, and then increase that value to induce sufficient speed or acceleration in the rotor.

[0044] An additional or further aspect of the invention involves amplifying the angle used to determine the positioning substitution signal based on the operating conditions or operating point of the electric motor. During motor operation, the pole or zero position of the regulating circuit is related to the operating conditions. This causes the regulation difference (i.e., the positioning substitution signal or angle) to be specifically affected near the pole or zero position, thereby ensuring reliable control and / or regulation of operation at all times. For example, the angle is here divided by the value of the drive control voltage or the rotational speed.

[0045] In one possible implementation, to obtain the voltage and / or current vectors, a Clark transformation, i.e., an ab or αβ transformation, is performed on the phase voltage or phase current. This means that the current and voltage vectors are generated in a coordinate system that is fixed relative to the stator. This improves the accuracy of the positioning substitution signal and thus enables particularly effective control and / or regulation of the electric motor, especially when starting from a standstill.

[0046] In an alternative implementation, the voltage and / or current vectors are determined using the Park transformation, or dq transformation. This means that the current and voltage vectors are generated in a coordinate system that is fixed relative to the rotor, i.e., rotating.

[0047] The electric actuator according to the invention is implemented, for example, as a regulating actuator for a motor vehicle. For this purpose, the actuator has a brushless and sensorless multiphase electric motor and a vectoring device for obtaining voltage and / or current vectors, as well as a controller for determining a positioning substitution signal. The actuator also has an observer for sensorlessly determining rotational parameters based on the positioning substitution signal, and a current regulator for controlling and / or regulating the electric motor, particularly by means of pulse width modulation or space vector modulation.

[0048] The driver, or vector device, and controller, along with the observer and current regulator, are typically (in terms of programming and / or circuitry) suitably adapted and configured to perform the methods described above. Therefore, the vector device is specifically configured to calculate the corresponding spatial vectors, i.e., voltage vectors and / or current vectors, based on determined, for example measured or calculated, phase voltages and / or phase currents. The calculated voltage vectors and / or current vectors are fed to the controller, which determines a positioning substitution signal based on the angles of the voltage vectors and / or current vectors.

[0049] The positioning substitution signal is fed to an observer, which evaluates the positioning signal, for example, after filtering (and similarly to a back EMF signal), and thus calculates or estimates the rotational parameters, namely rotor positioning and / or (rotor) speed. This calculated or estimated rotational parameter is then fed to the current regulator as a control parameter.

[0050] In a preferred design, the vector device and / or controller and / or observer and / or current regulator are formed at least in-chip by a microcontroller having a processor and data storage, wherein the functions for performing the method or respective method steps according to the invention are implemented in terms of programming techniques in the form of running software (firmware), so that the method or method steps (interacting with the user if necessary) are executed automatically when the running software is implemented in the microcontroller.

[0051] Within the scope of this invention, the vector device and / or controller and / or observer and / or current regulator are also formed from non-programmable electronic components, such as ASICs (Application-Specific Integrated Circuits) or FPGAs (Field-Programmable Gate Arrays), wherein the functions for performing the method are implemented using means of circuit technology.

[0052] Therefore, the drive or the electric motor operated by the method has better performance in starting or starting from a standstill and in continuous or sustained operation at low speeds.

[0053] In conceivable implementations, the electric motor is particularly connected to a bridge circuit of a current converter that transforms the DC voltage in the intermediate circuit into AC voltage for driving or operating the electric motor. Therefore, the driver has a DC voltage input or DC voltage interface. The bridge circuit is controlled and / or regulated, for example, by a current regulator in signal technology.

[0054] In the switching state of a power semiconductor switch relying on a bridge circuit, phase current flows through a shunt. For example, the voltage drop across the shunt is amplified and evaluated. The phase current is reconstructed using measurements and knowledge of the switching state of the power semiconductor switch. Alternatively, it is conceivable, for example, to measure the phase current directly or immediately. Therefore, along with the measured and / or calculated phase voltage, the phase voltage and phase current are provided to a vectoring device for obtaining the voltage vector and / or current vector.

[0055] In conceivable implementations, the vector device and the controller are, for example, implemented as a common component. Attached Figure Description

[0056] The embodiments of the present invention will now be explained in more detail with reference to the illustrations. These are presented in an illustrative and simplified manner:

[0057] Figure 1 An electric (motor-type) driver is shown, which has a current source and an electric motor, as well as a current converter wired between the two.

[0058] Figure 2 The driver with the phase voltage adjusted is shown;

[0059] Figure 3 The three-phase windings of a three-phase electric motor with a star-connected circuit are shown.

[0060] Figure 4 A bridge module is shown as a bridge circuit for a current converter of the phase windings of an electric motor.

[0061] Figure 5 The equivalent circuit diagram of the current source is shown;

[0062] Figure 6The controller and observer of the driver in the first embodiment are shown;

[0063] Figure 7 The controller and observer in the second embodiment are shown; and

[0064] Figures 8 to 10 The controller is shown in different implementations.

[0065] The corresponding parts and dimensions are always labeled with the same reference numerals in all drawings. Detailed Implementation

[0066] Figure 1 An electric actuator or electric motor type actuator 2 for an adjustment system (e.g., window regulator or seat adjustment unit) of a motor vehicle (not shown in detail) is illustrated. The actuator 2 includes a brushless and sensorless three-phase electric motor 4, which is connected to a current source (voltage supply) 8 via a current converter 6. In this embodiment, the current source 8 includes, for example, an in-vehicle energy storage device 10 in the form of a (motor vehicle) battery, and an intermediate (DC voltage) circuit 12 connected thereto, the intermediate circuit extending at least partially into the current converter 6.

[0067] The intermediate loop 12 is essentially formed by the supply line 12a and the return line 12b, which connect the current converter 6 to the energy storage device 10. Lines 12a and 12b are at least partially led into the current converter 6, in which an intermediate loop capacitor 14 and a bridge circuit 16 are connected between the lines.

[0068] During the operation of driver 2, the input current IE supplied to bridge circuit 16 is converted into three-phase output currents (motor current, three-phase current) IU, IV, IW for the three phases U, V, W of electric motor 4. These output currents IU, IV, IW, also referred to below as phase currents, are directed to the corresponding motor phases or phase (windings) U, V, W of the stator (not shown in detail). Figure 3 ).

[0069] Figure 3 The diagram shows a star circuit 18 with three phase windings U, V, and W. Phase windings U, V, and W are respectively guided to their respective bridge modules 26 of the bridge circuit 16 via (phase) ends 20, 22, and 24. Figure 3 They are connected to each other at star point 28 with opposite ends as a common connection interface.

[0070] exist Figure 3In the diagram, phase windings U, V, and W are shown using equivalent circuits in the form of inductors 30 and ohmic resistors 32, and their respective voltage drops 34, 36, and 38. The voltage drops 34, 36, and 38 across phase windings U, V, and W are schematically represented by arrows and derived from the sum of the voltage drops across inductors 30 and ohmic resistors 32 and the induced voltage or induced phase current 40. The phase current 40 (back electromotive force, back EMF) induced by the motion of the rotor of the electric motor 4... Figure 3 The middle part is schematically shown using circles.

[0071] The drive and control of the star circuit 18 are performed using a bridge circuit 16. The bridge circuit 16 is implemented, in particular, as bridge module 26 of the B6 circuit. In this design, during operation, the high (DC) voltage level of the supply line 12a and the low voltage level of the return line 12b are switched rhythmically at a high switching frequency on each phase winding U, V, W. The high voltage level is here, in particular, the intermediate circuit voltage UZK of the intermediate circuit 12, while the low voltage level is preferably the ground potential UG. This rhythmic drive and control is implemented as follows (in... Figure 1 (As indicated by the arrow) PWM control is performed by device 42, which acts as a regulator. This PWM control can control and / or adjust the speed, power, and direction of rotation of the electric motor 4.

[0072] Bridge module 20 includes two semiconductor switches 44 and 46, which are in Figure 3 The diagram only schematically and exemplaryly illustrates phase W. Bridge module 26 is connected to power supply line 12a via potential interface 48, and thus to intermediate loop voltage UZK. On the other hand, bridge module 26 is in contact with return line 12b via second potential interface 50, and thus to ground potential UG. The respective phase ends 20, 22, 24 of phases U, V, and W can be connected to either intermediate loop voltage UZK or ground potential UG via semiconductor switches 44 and 46. If semiconductor switch 44 is closed (conducting) and semiconductor switch 46 is open (not conducting), phase ends 20, 22, 24 will be connected to the potential of intermediate loop voltage UZK. Accordingly, when semiconductor switch 44 is open and semiconductor switch 46 is closed, phases U, V, and W are in contact with ground potential UG. Thus, by means of PWM control of device 42, it is possible to apply two different voltage levels to each phase winding U, V, and W.

[0073] Figure 4A simplified view of a single bridge module 26 is shown. In this embodiment, semiconductor switches 44 and 46 are implemented as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), which switch between on and off states rhythmically via PWM control. For this purpose, their respective gate interfaces are routed to corresponding control voltage inputs 52 and 54, through which signals from the drive unit 42 are transmitted.

[0074] Figure 5 An equivalent circuit diagram for current source 8 is shown. During operation, energy storage 10 generates a battery voltage UBat and a corresponding battery current IBat to power current converter 6. Figure 5 In the diagram, the internal resistor of the energy storage device 10 is shown as an ohmic resistor 56, and the self-inductor of the energy storage device 10 is shown as an inductor 58. A shunt resistor 60 is connected in the return line 12b, across which the intermediate loop voltage UZK drops.

[0075] exist Figure 1 In this embodiment, phase currents IU, IV, and IW are detected by ammeter 62 and directed to device 42. Vectoring device 64 determines the current vector and voltage vector in a coordinate system from the detected phase currents IU, IV, and IW and the calculated phase voltages UU, UV, and UW. The coordinate system can be an ab system fixed relative to the stator or a dq system fixed relative to the rotor, so that the corresponding current vector is referred to as Iab or Idq, and the voltage vector is referred to as Uab or Udq. The components of the current vector or voltage vector along the coordinate axes a, b, d, and q are correspondingly referred to as Ia, Ib, Id, Iq or Ua, Ub, Ud, Uq.

[0076] The current vectors Iab, Idq and the voltage vectors Uab, Udq are forwarded to the controller 66, which determines the positioning substitution signal PES based on the angle α of the voltage vectors and / or the current vectors Iab, Idq, Uab, Udq.

[0077] Angle α is determined, for example, by forming the phase difference between the current vectors Iab, Idq and the voltage vectors Uab, Udq, i.e., as the relative phase. For this purpose, the phase angles αU and αI of the voltage vectors Uab, Udq and the current vectors Iab, Idq are determined using an extended arctangent function, the so-called Arctan² function (atan²), and subsequently, the difference is formed. Therefore, for example, in the ab system:

[0078] α=atan2(Ua,Ub)-atan2(Ia,Ib).

[0079] Multiply the angle α, for example, by the magnification, sign, or scaling factor k1.

[0080] The positioning substitution signal PES is fed to observer 68, which filters the positioning substitution signal PES, for example, and calculates or estimates the rotational parameters θ and ω, i.e., rotor positioning θ and / or (rotor) speed ω. The calculated or estimated rotational parameters θ and ω are fed as control parameters to current regulator 70, which generates a PWM drive signal. Here, for example, it is possible to use the positioning substitution signal PES as the control parameter instead of the rotational parameter θ.

[0081] When calculating the rotation parameters θ and ω, it is preferable to form the difference between the expected values ​​θ and ω and the positioning substitution signal PES. This "error" is used as an adjustment difference to correct the expected values ​​θ and ω. Alternatively, the angle α can be used as an input parameter and interpreted as an "error" or "error signal" (mistake signal). This reduces the required computational load.

[0082] The current regulator 70 controls and / or regulates the operation of the electric motor 4, especially minimizing the angle α, preferably adjusting it to zero.

[0083] exist Figure 2 The following is a relatively simple illustration of an embodiment of the driver 2, which enables regulated operation of the phase voltage of the electric motor 4. In this embodiment, the vector device 64 or its function is integrated into the controller 66. In this embodiment, the phase currents IU, IV, IW and the phase voltages UU, UV, UW are directly measured or detected and transmitted to the controller 66.

[0084] In the following text, the various embodiments will be discussed in conjunction with... Figures 6 to 10 The functions of controller 66 and observer 68 will be explained in more detail.

[0085] According to Figure 6 In this embodiment, the rotor position θ determined by observer 68 is fed back to controller 66 and added to angle α to generate a positioning substitution signal PES. The rotor position θ is subtracted again in observer 68, and rotational parameters θ, ω are determined based on angle α. A typical method (such as incremental sensors) is used to obtain the positioning, which is then processed in the observer. This classic structure is reproduced using adders and subtractors, allowing the method to be easily implemented in existing systems.

[0086] To determine the rotational speed or velocity ω, the angle α is multiplied by the coefficient kw. The rotational speed ω is then calculated via time integrator 72. To determine the rotor position or rotor positioning θ, the angle α is multiplied by the coefficient kt, and then the change in rotational speed ω or rotor position is added. The new rotor position θ is then calculated by dividing by the past duration via divider 74.

[0087] According to Figure 7In this embodiment, angle α is directly sent to observer 68 as a positioning substitution signal (PES). Therefore, controller 66 generates angle α as an error signal or adjustment difference for observer 68.

[0088] Figure 8 An embodiment of controller 66 is shown, which is particularly suitable for and configured for use with Figure 2 The driver 2 is shown. In this embodiment, the current regulator 70 adjusts the current along the q direction of the positioning estimate. This means that the current component Id is made equal to zero (Id = 0). As a result, the positioning direction and the current vector Iab are offset by 90° or π / 2, or by a phase angle P. This enables a simplified design of the controller 66.

[0089] According to Figure 9 In this embodiment, the current is regulated by the current regulator 70 along the q direction of the positioning estimate (Id = 0). Therefore, observing only the voltage component Ud is sufficient to identify whether the phase voltage leads or lags the phase current. In an embodiment without feedback of the rotor position θ, the voltage component Ud or the corresponding angle α is multiplied by a coefficient k1 equal to -1 (k1 = -1) and sent as the positioning substitution signal PES.

[0090] Figure 10 The embodiment illustrates an implementation of the controller 66 in the calibrated state of the electric motor 4. If the electric motor 4 is calibrated, the positioning direction and voltage vectors Uab and Udq are deviated by 90° or π / 2, or by a phase angle P. In this embodiment, the voltage angle αU is multiplied by a coefficient k1 = 2. In other words, the adjustment is performed on the square of the phase voltage. The phase angle P is then subtracted, resulting in a difference with the current angle αI, to generate the angle α or positioning substitution signal PES.

[0091] This invention is not limited to the embodiments described above. Instead, other variations of the invention can be deduced by those skilled in the art without departing from the subject matter. In particular, all individual features related to the embodiments can be combined with each other in other ways without departing from the subject matter.

[0092] The control or regulation method or device 42 can be combined with the initial positioning method or positioning identification method.

[0093] Furthermore, one could conceive of a scenario where the speed of the observer 68 used to calculate the rotational parameters θ and ω is limited to a minimum. Thus, even when the values ​​at the input of the observer 68 remain constant, the calculated rotational parameters θ and ω are increased with minimal gradient.

[0094] For example, it is possible that the angle α used to determine the positioning substitution signal PES is amplified by a coefficient k1, depending on the operating condition or operating point of the electric motor 4. Preferably, the minimum speed is also adjusted or changed depending on the operating point or operating condition of the electric motor 4. Preferably, the value of the minimum speed is adjusted here, particularly in relation to temperature.

[0095] List of reference numerals

[0096] 2 drives

[0097] 4 Electric motors

[0098] 6 Current converter

[0099] 8 Current Source

[0100] 10 Energy Storage Device

[0101] 12 Intermediate loops

[0102] 12a Supply Line

[0103] 12b Return Line

[0104] 14. Intermediate circuit capacitor

[0105] 16 Bridge circuit

[0106] 18. Star circuit

[0107] Phase ends of phases 20, 22, and 24

[0108] 26 Bridge Modules

[0109] 28 star points

[0110] 30 Inductors

[0111] 32 Resistor

[0112] Voltage drop at 34, 36, and 38

[0113] 40-phase current

[0114] 42 Equipment / Regulator

[0115] 44, 46 Semiconductor switches

[0116] 48 and 50 voltage interfaces

[0117] 52, 54 Control voltage input terminals

[0118] 56 Resistor

[0119] 58 Inductors

[0120] 60 shunt resistor

[0121] 62 Ammeter

[0122] 64 Vector Device

[0123] 66 Controller

[0124] 68 Observer

[0125] 70 Current Regulator

[0126] 72 Integrator

[0127] 74 Divider

[0128] IE Input Current

[0129] IU, IV, IW phase currents

[0130] U, V, W phases

[0131] UZK intermediate circuit voltage

[0132] UG grounding potential

[0133] IBat battery current

[0134] UBat battery voltage

[0135] UU, UV, UW phase voltages

[0136] Iab, Idq current vectors

[0137] Uab, Udq voltage vectors

[0138] Ia, Ib, Id, Iq Current vector components

[0139] Voltage vector components Ua, Ub, Ud, Uq

[0140] αI Current angle / phase

[0141] αU Voltage angle / phase

[0142] α angle

[0143] PES Positioning Alternate Signal

[0144] coefficients k1, kw, and kt

[0145] θ Rotational parameter / rotor position

[0146] ω Rotational parameter / rotational speed

[0147] P Phase angle / bias

Claims

1. A method for operating a brushless and sensorless multiphase electric motor (4), - in, Determine at least two phase voltages (UU, UV, UW) and at least two phase currents (IU, IV, IW) of the electric motor (4). - Wherein, the voltage vector (Uab, Udq) is obtained from the phase voltage (UU, UV, UW) and the current vector (Iab, Idq) is obtained from the phase current (IU, IV, IW). - Wherein, a positioning substitution signal (PES) is determined as a measure of rotor positioning (θ) based on the angle (α) determined by the difference between the angle (αI) of the current vector and the angle (αU) of the voltage vector. - Wherein, rotation parameters (θ, ω) are calculated based on the positioning substitution signal (PES), and - Wherein, the electric motor (4) is controlled and / or adjusted according to the rotation parameters (θ, ω).

2. The method according to claim 1, Its features are, The additional phase angle (P) is taken into account when determining the angle (α).

3. The method according to claim 1 or 2, Its features are, Control and / or adjust the electric motor (4) to minimize the angle (α).

4. The method according to claim 1 or 2, Its features are, The phase voltage (UU, UV, UW) of the electric motor (4) is controlled and / or adjusted according to the rotational parameters (θ, ω).

5. The method according to claim 1 or 2, Its features are, The rotational parameters (θ, ω) are limited based on the saved minimum speed.

6. The method according to claim 5, Its features are, The value of the minimum speed is adjusted in relation to temperature.

7. The method according to claim 1 or 2, Its features are, The angle (α) used to determine the positioning alternative signal (PES) is amplified depending on the operating conditions.

8. The method according to claim 1 or 2, Its features are, In order to obtain the voltage vector (Uab) and / or the current vector (Iab), a Clarke transformation is performed on the phase voltage (UU, UV, UW) or the phase current (IU, IV, IW).

9. An electric drive (2) for performing the method according to any one of claims 1 to 8, the drive having - Brushless and sensorless multiphase electric motor (4). - Vector device (64) for obtaining voltage vector (Uab, Udq) and current vector (Iab, Idq). - Controller (66) for determining positioning alternative signals (PES). - An observer (68) for sensorless determination of rotational parameters (θ, ω), and - A current regulator (70) for controlling and / or regulating the electric motor (4).

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